Biology Lab - Standards 9h, 9i
How does exercise affect the rate at which your heart beats?  

 Purpose: To what extent does exercise affect the rate at which your heart beats?

State Standards­: 9h, 9i
As a result of the coordinated structures and functions of organ systems, the internal environment of the human body remains relatively stable (homeostatic), despite changes in the outside environment.

Background: The heart is made out of cardiac muscle tissue and like all muscles in the human body needs to be exercised in order to remain healthy. Exercise works to strengthen your skeletal muscles as well as your cardiac muscle. As a person exercises, need for oxygen increases for muscles. The heart must beat faster in order to supply the body’s muscles with more oxygen. Increased heart rate increases the blood flow to the lungs which in turn increases the amount of oxygen that can be delivered to the body’s muscles.

Materials: Lab, paper, pencil, stopwatch or classroom timer.

Procedure:

1. Rest quietly until you are fully relaxed.
2. Find your pulse on your neck using your forefingers.
3. Have your partner time you for one minute while you count how many times your heart beats in one minute. Record this number in your results chart.
4. Repeat steps 2 and 3 for a second trial.
5. Have your partner time you while you do an exercise of choice, either sprinting, jumping jacks, jogging, hopping, or any other highly cardiovascular exercise. Exercise for the entire two minutes or until you are out of breath.
6. Immediately after you finish your exercise, count the number of times your heart beats in one minute until your heart beat rate returns to its resting level.
7. Once your heartbeat equals that of your original resting rate record the rate for one more minute.
8. Record all data in your data chart.
9. Switch roles and now time your partner.
10. Draw a line graph from the results you have entered in the data table for both you and your partner.

Data:

Graph:

minutes after exercise

Conclusion: Please answer the following questions on a separate piece of lined paper:

1. What is your normal pulse rate at rest?
2. What is your partners?
3. What is your maximum pulse rate?
4. What is your partners?
5. After exercising how long did it take for your pulse rate to return to normal?
6. How long for your partners?
7. Explain why your heart beats faster than normal when you exercise.
8. Explain why there might be differences between your partner’s heart rate and yours.
9. Give three examples of activities that might strengthen your heart.
10. Give three reasons why it is important to strengthen your heart .